Here it is, the long awaited (or maybe just vastly overlooked) LED instrument light How-To.
First thing's first, yank the cluster and get rid of all the green plastic. Replace it with part of an old jug or whatever across the top to act as a diffuser and put the digital clock back together without it. Assuming you've gotten that far, you now have a sickly yellowish colored light thanks to the wonderful world of incandescents. Well, that's what we're here to fix and so fix it we shall. Let's go LED on this bad boy.
You're going to need some soldering skills for this one, a total of seven components from RadioShack, solder, flux, wire and shrinkwrap. The bill should come to about $30 if you go for white (plus $10 for the soldering wand if yours gives up the ghost halfway through the job like mine did) and as little as $10 if you want to go red, green or amber.
schematic used without permission
The first thing you will notice is that this schematic uses 4 LEDs while our Foxes use 3 instrument lights. Not a problem, just drill a 5mm hole in between the two top lights and drop your fourth bulb in there.
Please excuse the quality of pic, cheap digicam is better than none.
Here's where I placed my 4th LED, gives it a nice, even glow all the way across the top of the cluster.
This is your old instrument light with the bulb removed from the holder.
And the holder with a 5mm LED inseted into it.
Now, to get into making this work on the Fox. The first thing I did was tap into the light circuit, that's the black jumper wire all the way on the end. The capacitor was soldered to one end of that jumper and the power lead to my LEDs was tacked on to the other side.
Running the wires was more trial and error than anything, but as long as you follow the schematic, it shouldn't give you any trouble. The two LEDs with holders made up my first pair, then power was sent through the load regulator (LM317 and 30 Ohm resistor) so the lights didn't explode under 12 volts. That would be what we in the technical field call a 'Bad Thing'(TM). Then the same deal with wiring in the light behind the digital clock and the 4th lamp mounted up between the first two. From the second set of lights, I ran a wire to the other end of the capacitor and then to ground. One of the nuts on the back of the tach grounds to the same circuit as the instrument lights. Bonus!
Then the LM317 Adjustable Voltage Regulator was affixed using a factory fastener (white plastic piece between the LM317 and the cluster circuit to maintain a clean ground line) and it was all ready for installation into the car.
Parts list: (With RS Catalog #s)
4 matched 5mm LEDs (3.6V 20ma) - My white 1100MCD ones were $4.99 each (Cat#276-320), blues run $3.99 for 2600 MCD intensity(Cat# ) with reds emitting 3000 MCD for $1.99(Cat# 276-307) and Yellow 1900 MCD intensity going for $2.49 (Cat# 276-351). Note: Those yellows are 40mA load rather than 20mA, so each single LED will replace a pair on the schematic.
30 Ohm 1/4W resistor - Couldn't find a 30, but RadioShack had 5 10s for $0.99 and three of those together gave me what I needed. (Cat# 271-1301)
0.1uF capacitor - Another 99 cent part, came in a pack of two for that price. (Cat# 272-135)
LM317 Adjustable Voltage Regulator - A whopping $1.99 (Cat# 276-1778)
Shrinkwrap and wire - Had these laying around, probably $3 to buy more than enough for 5 of these jobs.
Ther you have it, anyone with moderate electronics assembly skill should be able to knock one of these together in a couple hours and run with custom LED instrument lights. The best part is, the variable voltage means my light dimmer still works.
Good luck out there, and be careful with that soldering wand.
(for hobbyist use only, not my problem if you fry your car, yourself, burn down your house or explode ceramic components in your face causing disfiguration and/or loss of job)
Modified by Ol' Grey Fox at 11:57 PM 10-22-2003
Modified by Ol' Grey Fox at 12:20 AM 10-23-2003